Many objectives may be achieved by exposing a pumpable substance, for example, any pumpable food substance, to ultrahigh-pressure. For example, many fresh food products may be pasteurized by exposing them to ultrahigh-pressure for a selected amount of time, thereby killing microorganisms. Ultrahigh-pressure may also be used to render a desired physical change in a food product, for example, to improve moisture retention, to cause gelation of starchy suspensions, or to raise the melting point of butter and soft fats. Ultrahigh-pressure processing may be used to improve the quality of existing products, and to generate new products.
Currently, the majority of pressure-based food processing is achieved by loading a food product into a large pressure vessel. Typically, the food is prepackaged in flexible packets. The pressure vessel is then closed and pressurized to a selected pressure. This pressure is maintained for a selected amount of time, commonly referred to as the "dwell time," to achieve the desired physical change in the food product. The vessel is then depressurized, and the contents unloaded.
Although current systems produced desirable results, they also have several disadvantages. For example, large pressure vessels are costly to construct. These current systems are also time consuming to use, given the nature of the processing.